MCU Functionality Problems at Higher Frequencies

Question:

My MCU does not work properly with higher operational frequencies. What are the possible causes?

Answer:

Please check the following items:

1) Make sure that both the operating frequency and operating voltage are set within the allowable range.

2) Depending on the MCU, you must change the access cycles of the operational power control state, code flash, RAM, etc. To change the access cycles, check the operational power control register (OPCCR), or the MEMWAIT bit setting of the memory cycle wait setting register (MEMWAIT).